JP2014218953A - Engine cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine cooling system which effectively improves fuel consumption.SOLUTION: An engine cooling system comprises: a Rankine cycle device 50 in which an evaporator 52, an expander 53, a condenser 54, and a compressor 55 are arranged in order in a circulating flow path 51; a cylinder block inner flow path 31 formed inside a cylinder block; a main flow path 33 that passes through the evaporator 52 from a downstream end of the cylinder block inner flow path 31; a radiator 36 that further cools with outside air the cooling water cooled by the evaporator 52; and a sub-flow path 37 and a cooling flow path 39 that branch off from the main flow path 33 on the downstream side of the evaporator 52, which pass through the radiator 36 and the condenser 54, and which are connected to the main flow path 33 on the downstream side of the evaporator 52.

Description

  The present invention relates to an engine cooling system, and more particularly to an engine cooling system using a Rankine cycle device.

  Conventionally, in order to improve the cooling performance of the engine, a cooling system in which a main radiator and a sub radiator are arranged in series or in parallel in a cooling water circulation path is known. In such a cooling system, the cooling water heated by the engine is cooled by the main radiator and then further cooled by the sub-radiator and introduced into the intercooler or the like.

JP 2008-38891 A JP 2011-190743 A

  2. Description of the Related Art In recent years, with the increase in engine output, a radiator has been required to have high cooling performance especially during high load operation such as when traveling on an uphill. In order to further improve the cooling performance, it is necessary to increase the size of the radiator and the fan, but it is difficult due to restrictions such as the in-vehicle layout and installation space. Further, if the number of installed radiators and fans is increased, the pressure loss of the radiator and the engine load due to the driving of the fan increase, which causes a problem of deterioration in fuel consumption.

  An object of the present invention is to provide an engine cooling system capable of effectively improving the fuel efficiency of an engine while recovering waste heat.

  In order to achieve the above object, an engine cooling system according to the present invention includes a first heat exchanger that heats a working fluid, a expander that expands the heated working fluid, A second heat exchanger for cooling the working fluid, a Rankine cycle device in which a compressor for pumping the cooled working fluid is disposed in order, a first cooling water passage formed in a cylinder block of the engine, and the first A second cooling water flow path that is connected to the upstream end of the first cooling water flow path from the downstream end of the cooling water flow path via the first heat exchanger, and is provided with a pump for pumping the cooling water; A radiator for further cooling the cooling water cooled by the first heat exchanger with outside air, and a branch from the second cooling water flow path downstream of the first heat exchanger, and the radiator, the second heat Through the exchanger To, characterized in that it and a third cooling water passage connected to the second cooling water passage downstream of the first heat exchanger.

  A recirculation exhaust cooler that is provided in a recirculation exhaust flow path that connects an intake system and an exhaust system of the engine and that cools the recirculation exhaust with cooling water; and a second cooling water flow path downstream of the first heat exchanger. And a fourth cooling water passage connected to the second cooling water passage on the upstream side of the first heat exchanger via the reflux exhaust cooler. .

  According to the engine cooling system of the present invention, it is possible to effectively improve the fuel efficiency of the engine while recovering waste heat.

1 is a schematic overall configuration diagram showing an engine cooling system according to an embodiment of the present invention. It is a typical whole block diagram which shows the cooling system of the engine which concerns on other embodiment.

  Hereinafter, an engine cooling system according to an embodiment of the present invention will be described with reference to FIG. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  First, the overall configuration of an intake / exhaust system to which the cooling system according to the present embodiment is applied will be described.

  As shown in FIG. 1, an intake passage 11 is connected to an intake manifold 10a of a diesel engine (hereinafter simply referred to as an engine) 10, and an exhaust passage 12 is connected to an exhaust manifold 10b. In the intake passage 11, a turbocharger compressor 13 and an intercooler 14 for cooling the intake air are arranged in this order from the intake upstream side, and in the exhaust passage 12, a supercharger turbine 15 is arranged. Further, the engine 10 is provided with an exhaust gas recirculation device (Exhaust Gas Recirculation: hereinafter referred to as EGR device) 20 that recirculates a part of the exhaust gas to the intake system.

  The EGR device 20 includes a first EGR cooler 22, a second EGR cooler 23, and an EGR valve 24 arranged in this order in an EGR passage 21 that connects the exhaust passage 12 and the intake passage 11. The first EGR cooler 22 and the second EGR cooler 23 are connected to a later-described EGR cooler flow path 38 to cool the EGR gas with the cooling water of the engine 10.

  Next, the overall configuration of the cooling system according to the present embodiment will be described.

  As shown in FIG. 1, the cooling water circuit includes a cylinder block internal flow path 31 having a water jacket and the like, a main flow path 33 in which an evaporator 52 of a Rankine cycle device 50 described later is interposed, and a bypass flow that bypasses the evaporator 52. Cooling branched from the passage 35, the sub flow path 37 in which the radiator 36 and the intercooler 14 are interposed, the EGR cooler flow path 38 in which the first EGR cooler 22 and the second EGR cooler 23 are interposed, and the sub flow path 37. A flow path 39 is provided.

  In this embodiment, the in-cylinder block flow path 31 is the first cooling water flow path of the present invention, the main flow path 33 is the second cooling water flow path of the present invention, the sub flow path 37 and the cooling flow path 39 are the present invention. The third cooling water flow path and the EGR cooler flow path 38 correspond to the fourth cooling water flow path of the present invention.

  The main flow path 33 is connected from the outlet part (downstream end) of the in-cylinder block flow path 31 to the inlet part (upstream end) of the in-cylinder block flow path 31 via the evaporator 52. The main flow path 33 is provided with a thermostat 41 and a cooling water pump 42 on the downstream side of the evaporator 52 immediately downstream of the branch portion with the bypass flow path 35. The cooling water pumped by the cooling water pump 42 flows through the bypass passage 35 when the engine 10 is warmed up, and is introduced into the evaporator 52 when the warming up is completed.

  The radiator 36 further cools the cooling water cooled by the evaporator 52 by exchanging heat with the outside air. The radiator 36 has a known structure in which a tube (not shown) serving as a cooling water flow path is meandered, and a plurality of fins (not shown) for heat exchange are provided between the meandering tubes. Has been.

  The sub flow path 37 branches from the main flow path 33 on the downstream side of the cooling water pump 42, passes through the radiator 36 and the intercooler 14, and then the main flow path 33 between the evaporator 52 and the cooling water pump 42. It is connected to the. The sub-channel 37 is provided with a thermostat 43 that introduces cooling water into the intercooler 14 according to the cooling water temperature.

  The EGR cooler flow path 38 connects the main flow path 33 downstream of the cooling water pump 42 and the main flow path 33 downstream of the bypass flow path 35, and the first EGR cooler 22 and the second EGR cooler. Each branch is formed so as to pass through each of 23.

  The cooling flow path 39 branches off from the sub flow path 37 between the radiator 36 and the intercooler 14, and passes through the condenser 54 of the Rankine cycle device 50 described later, and is located on the downstream side of the evaporator 52. 33.

  The Rankine cycle apparatus 50 has a known structure, and is configured by sequentially arranging an evaporator 52, an expander 53, a condenser 54, and a compressor 55 in a circulation channel 51 in which a working fluid is sealed. In the present embodiment, the evaporator 52 corresponds to the first heat exchanger of the present invention, and the condenser 54 corresponds to the second heat exchanger of the present invention.

  The evaporator 52 is supplied with cooling water heated by the in-cylinder block flow path 31 and cooling water heated by the EGR coolers 22 and 23 via the main flow path 33. The evaporator 52 heats and vaporizes the working fluid by exchanging heat between the high-temperature cooling water introduced from the main flow path 33 and the working fluid. The expander 53 is a turbine or the like driven by the vaporized working fluid, and converts the thermal energy of the working fluid into power (rotational force). A power generator 60 is connected to the expander 53.

  Cooling water cooled by the radiator 36 is introduced into the condenser 54 through the cooling flow path 39. The condenser 54 cools the expanded working fluid by exchanging heat between the low-temperature cooling water introduced from the cooling flow path 39 and the working fluid. The compressor 55 is driven by the power of the engine 10, for example, and pumps the working fluid cooled by the condenser 54 to the evaporator 52.

  That is, the Rankine cycle device 50 uses the temperature difference between the evaporator 52 heated by the high-temperature cooling water and the condenser 54 cooled by the low-temperature cooling water to drive the expander 53, thereby eliminating the waste heat of the cooling water. Is recovered as power. Since the power generator 60 is connected to the expander 53, the recovered power can be converted into electric energy.

  Next, the effect by the cooling system which concerns on this embodiment is demonstrated.

  In the cooling system of the present embodiment, the high-temperature cooling water heated by the in-cylinder block flow path 31 and the EGR coolers 22 and 23 is introduced into the evaporator 52 of the Rankine cycle apparatus 50 via the main flow path 33. The high-temperature cooling water introduced into the evaporator 52 is cooled by exchanging heat with the working fluid and then introduced into the in-cylinder block flow path 31 again. That is, the evaporator 52 is configured to effectively cool the high-temperature cooling water heated in the cylinder block flow path 31 and the like without using a large main radiator or fan as in the conventional cooling system.

  Therefore, according to the cooling system of the present embodiment, the main radiator and the fan are not required, the pressure loss of the main radiator and the engine load due to the driving of the fan are reduced, and the fuel efficiency can be effectively improved.

  Further, in the cooling system of the present embodiment, the low-temperature cooling water cooled by the radiator 36 is introduced into the condenser 54 of the Rankine cycle device 50 via the sub flow path 37 and the cooling flow path 39. The low-temperature cooling water introduced into the condenser 54 cools the working fluid expanded by the expander 53. And the expansion machine 53 drives using the temperature difference of the evaporator 52 and the capacitor | condenser 54, and the waste heat of cooling water is collect | recovered as motive power. Further, the recovered power is converted into electric energy when the generator 60 is driven by the expander 53.

  Therefore, according to the cooling system of this embodiment, it is possible to effectively recover the waste heat of the cooling water and use it as electric energy while improving the fuel efficiency. By driving the auxiliary machinery of the engine 10 using the obtained electrical energy, the load on the engine 10 can be further reduced and the fuel consumption can be further improved.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, when cooling the EGR gas, as shown in FIG. 2, the EGR cooler flow path 38 may be branched from the sub flow path 37 on the downstream side of the radiator 36. Also in this case, the same effect as the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10 Engine 14 Intercooler 20 EGR apparatus 22 1st EGR cooler 23 2nd EGR cooler 31 Flow path in cylinder block 33 Main flow path 35 Bypass flow path 36 Radiator 37 Sub flow path 38 Flow path for EGR cooler 39 Cooling flow path 50 Rankine cycle Device 51 Circulation channel 52 Evaporator 53 Expander 54 Condenser 55 Compressor

Claims (2)

A first heat exchanger that heats the working fluid in a circulation channel enclosing the working fluid, an expander that expands the heated working fluid, a second heat exchanger that cools the expanded working fluid, and a cooled operation A Rankine cycle device in which compressors for pumping fluid are sequentially arranged;
A first cooling water passage formed in the cylinder block of the engine;
Second cooling provided with a pump connected to the upstream end of the first cooling water flow path from the downstream end of the first cooling water flow path via the first heat exchanger and pumping the cooling water. A water channel,
A radiator for further cooling the cooling water cooled by the first heat exchanger with outside air;
The second cooling water flow is branched from the second cooling water flow path on the downstream side of the first heat exchanger, and the second cooling water flow on the downstream side of the first heat exchanger via the radiator and the second heat exchanger. An engine cooling system comprising: a third cooling water flow path connected to the road. A recirculation exhaust cooler that is provided in a recirculation exhaust flow path that connects the intake system and the exhaust system of the engine and cools the recirculation exhaust with cooling water;
Branched from the second cooling water flow path downstream of the first heat exchanger and connected to the second cooling water flow path upstream of the first heat exchanger via the reflux exhaust cooler The engine cooling system according to claim 1, further comprising a fourth cooling water flow path.

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